In 1981 Louisiana enacted the Balanced Treatment for Creation-Science and Evolution-Science in Public School Instruction Act, commonly called the Creationism Act. It did not require that either evolution or creationism be taught in public schools. However, the act stated that if one theory is presented, then the other must be as well. According to supporters, the bill had a secular purpose, which was “protecting academic freedom.” However, opponents of the law, including high-school teacher Don Aguillard, charged that it was a violation of the establishment clause and filed suit; Edwin Edwards, as the governor of Louisiana, was named as one of the respondents.

A federal district court granted Aguillard a summary judgment, noting that there was no secular reason for barring the instruction of evolution. Moreover, the court held that the statute promoted a particular religious doctrine. The decision was affirmed by the appellate court, which found that the law’s purpose was “to discredit evolution by counterbalancing its teaching at every turn with the teaching of creationism, a religious belief.”

The case was argued before the U.S. Supreme Court on December 10, 1986. In its review the court used the so-called Lemon test, which determines whether a statute is permissible under the establishment clause. In Lemon v. Kurtzman (1971) the court held that the statute must have a “secular legislative purpose,” its primary effect must be one that neither advances nor inhibits religion, and it cannot create “an excessive government entanglement with religion.” If any of the conditions are violated, the statute is unconstitutional. In examining the Creationism Act’s purpose, the court rejected the state’s claims that the law was designed to protect academic freedom and that it advanced a “basic concept of fairness.” The court held that the act did not grant teachers greater flexibility. The court further found that the Creationism Act was discriminatory by requiring the development of curricular guidelines and research for creation science to the exclusion of evolution. Moreover, according to the court, the act did not ensure a more-complete science curriculum. If the Louisiana legislature was attempting to maximize the comprehensiveness and effectiveness of science instruction, the court reasoned, it would have included the teaching of all scientific theories about the origins of humankind.

The Supreme Court held that the state legislature had a preeminent religious purpose in enacting the statute. The court believed that the state legislature was attempting to advance the religious viewpoint that a supernatural being created humankind. The court thus ruled that the state statute was unconstitutional because it violated the establishment clause. The decision of the appellate court was upheld.